1. Field of the Invention
The invention relates to an injection unit of an injection molding machine, and more particularly, an injection unit that includes a plastication cylinder which facilitates high injecting pressures.
2. Description of the Related Art
During the past few years attempts have been made to replace hydraulic drives for injection molding machines by electric drives, because the control of the latter can be more easily mastered. As electric drives for the clamping unit and the injection unit of injection molding machines frequently screwed drives are used in which the movable tool clamping plate or a screw of the injection unit is operated via a worm gear spindle. It is a drawback in solutions of this type that for applying the clamping forces of the high injecting pressure considerable axial forces act upon the screwed drive and can destroy the same. In order to eliminate this drawback, the screwed drive can be hydraulically supported, for instance, while high forces are applied. Such solution is disclosed, for instance, in DE 101 04 109 A1 and EP 0 760 277 B1. In said known solutions a worm gear spindle actuating the screw of the injection unit is supported via a hydraulic cylinder, the piston rod thereof being connected to the worm gear spindle. Such hybrid solutions having an electric drive and a hydraulic support require a comparatively high expenditure in terms of devices and energy.
Compared to this, the object underlying the invention is to provide an injection unit of an injection molding machine or the like by which high injecting pressures can be applied and which has a reduced energy demand vis-à-vis conventional solutions.